A high-pressure bow shock wave can be caused by a spacecraft flying at a hypersonic/high supersonic speed. An extreme heat experienced by the spacecraft is caused by a high-pressure bow shock wave in front of the spacecraft, during atmospheric reentry.
The high-pressure bow shock is where the atmosphere is rapidly compressed by a factor of 50 to 100 depending on the speed of the spacecraft. Because of this rapid compression, the gas is heated to temperatures of about 2000° C. to 2500° C. This hot gas impinges on the front of the spacecraft, transferring the extreme heat to the front surface of the spacecraft.
One way to withstand the extreme heat harmlessly is by ablation (melting/vaporizing/breaking off layers of materials). Another way to withstand the extreme heat harmlessly is by dissipation rather than ablation.
Many heat shield concepts for minimizing heat transfer to the spacecraft structure, during atmospheric reentry are known. However, known heat shields comprised of carbon phenolic are relatively heavy and cause a significant weight penalty to the spacecraft. Conventional carbon-carbon heat shields have a relatively high thermal conductivity, which can cause overheating at the heat shield-spacecraft structure interface, during atmospheric reentry.
Some available heat shield materials, such as phenolic impregnated carbon ablator (PICA) have manufacturing limitations and surface pressure limitation.